Improvement in lifting-jacks



D. T. W ELC H.

Lifting-lacks.

PatentedNov. 24,1874.

, a I mmm UNITED STATES PATENT OFFICEo DAVID T. 4WELCH, OF ST. LOUIS, MISSOURI.

IMPROVEMENT IN LlFTlNG-JACKS.

Specification forming part of Letters Patent No. 157,254, dated November 24, 1874 g application lled October 20, 1874.

To all whom it may concern:

Beit known that I, DAVID T. WELCH, of St. Louis, in the State of Missouri, have invented an Improved Screw-Jack for Lifting or Applying' Pressure; and I do hereby dclare the following to be afull and correct description of the same, reference being had to the accompanying drawings, in which- Figure lis a side elevation, partly in section, of my machine. Fig. 2 is a horizontal section 011 line x at of Fig. l.

The same letter indicates the same part in both Iigures.

My invention consists in the construction, substantially as hereinafter described, of a machine or instrument for the. more convenient application ofthe power of the screw,either for raising weights or for effectin g compression in either direction.

The drawing represents a machine embodying the principle of my invention, applicable to the handling of railroad-iron, to the lifting of heavy weights, and to the production of powerful upward pressure.

In the drawing, A A mark the u'feet of the machine, which support two uprights, B B, united at top by a cross-beam, O. These together form a gallows of convenient shape for straddling the work. A large screw, S, passes down through an opening in the middle of the cross-beam C. Upon it is a large nut, N, held in position by the yokebea1n D, as shown in Fig. l. The nut is circular in shape, as

. seen in Fig. 2, and has cut upon its perimeter a thread to receive and engage the threads of a worm, W', on the horizontal shaft F. The journals of this shaft turn in boxes in the ends of the arms E E. They project beyond the ends of the frame, and either or both may have a crank, K, attached, by which the shaft F can be rotated. Swiveling on the top of the screw S is a platen, H, intended for use when the machine is employed as a press. On the lower end ofthe screw is a swivel, to which is affixed a grapnel for holding the weight to be lifted. (In this case shown as a railroad-rail.) Above the screw-thread a hand-wheel, G, is fixed to the screw S, by which the screw may be rotated.

The operation is as follows: The machine being placed astraddle of the work, the weight to be lifted is grasped by the grapnel. The hand-wheel G is then operated, turning the screw S in the direction to raise it. When the strain becomes too heavy'to be raised by the hand-wheel, the crank K is called into use, turning the worm W and the nut N. The weight not being allowed to rotate, the turn- 'ing ofthe nut in the proper direction will raise the screw S and the weight attached to it.

By proper graduation of the pitch of the worm, nut, and screw-threads, and of the length of the crank-arm, any desired multiplication of the applied power can be effected.

It is obvious that, by the same arrangement of mechanism, a press of great power can be produced by the addition of the necessary platens.

Having thus described my invention, what I claim, and desire to secure byLetters Patent, 1s`

The combination of the uprights B B, crossbeam O, and yoke-beam D with the crank K, shaft F, worm W, nut N, and screw S, provided with a swivel and grapnel, all constructed substantially as and for the purpose set fort-h.

The above specification of my said invention signed and witnessed at St. Louis this 23d day of September, A. D. 1874.

DAVID T. WELCH. Witnesses:

GEo. W. GRIFFIN, THos. WEBsTER. 

